Re: [PATCH v3 6/6] iommu: mtk_iommu: Lookup phandle to retrieve syscon to pericfg

From: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
To: Yong Wu <yong.wu@mediatek.com>
Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	krzysztof.kozlowski@linaro.org, iommu@lists.linux-foundation.org,
	robh+dt@kernel.org, linux-mediatek@lists.infradead.org,
	krzysztof.kozlowski+dt@linaro.org, matthias.bgg@gmail.com,
	will@kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 6/6] iommu: mtk_iommu: Lookup phandle to retrieve syscon to pericfg
Date: Mon, 13 Jun 2022 10:13:13 +0200	[thread overview]
Message-ID: <80c7fa61-e25a-fc45-bdcb-60ac3796b96e@collabora.com> (raw)
In-Reply-To: <db422fe4d0b5391ee2aacae989d7e48209e1095f.camel@mediatek.com>

Il 13/06/22 07:32, Yong Wu ha scritto:
> On Thu, 2022-06-09 at 12:08 +0200, AngeloGioacchino Del Regno wrote:
>> On some SoCs (of which only MT8195 is supported at the time of
>> writing),
>> the "R" and "W" (I/O) enable bits for the IOMMUs are in the
>> pericfg_ao
>> register space and not in the IOMMU space: as it happened already
>> with
>> infracfg, it is expected that this list will grow.
> 
> Currently I don't see the list will grow. As commented before, In the
> lastest SoC, The IOMMU enable bits for IOMMU will be in ATF, rather
> than in this pericfg register region. In this case, Is this patch
> unnecessary? or we could add this patch when there are 2 SoCs use this
> setting at least?  what's your opinion?
> 

Perhaps I've misunderstood... besides, can you please check if there's any
other SoC (not just chromebooks, also smartphone SoCs) that need this logic?

Thanks,
Angelo

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